It is well known that uncontrolled growth of microorganisms in a water cooling system (that recirculates the water) can lead to deposit formation which contributes to fouling, corrosion and scale. Slimes can clog piping, hinder heat transfer or otherwise interfere with the proper functioning of a water cooling system. Presence of algae, Chroococcus, Oscillatoria and Chlorococcus in water cooling systems have been identified as causing fouling. In addition, algal slimes seem to become habitat for corrosive bacteria, and perhaps pathogenic bacteria.
Alginic acid (alginate) which is a polysaccharide constitutes the main element of algal cell walls. In some species of algae such as Fucus distichus, alginate makes up to 60% of the total cell wall. In addition to algae, some bacteria common in cooling waters, e.g., Pseudomonas spp. produce an extracellular polysaccharide polymer (slime) which results in fouling, formation of gases and protection of corrosive bacteria in water cooling systems. The extracellular polysaccharide polymer (slime) produced by some Pseudomonas spp. has been identified as alginate (L. R. Evans et al., J. Bacteriol. 1973, 116:915-924).
Alginate is a copolymer of three main structural blocks, poly-beta-D-mannuronic acid (poly-M), poly-alpha-L-guluronic acid (poly-G), and blocks in which both uronic acids occur in what is believed to be an alternating sequence (poly-MG) (A. Haug et al., Acta Chem. Scand. 1967, 21:691-704).
Thus, the action of enzymes such as alginate lyases capable of depolymerizing alginate in the algal cell wall and slimes from Pseudomonas spp. can cause lysis of these organisms and/or increase the susceptibility of these organisms to the chemical biocides which customarily are in water cooling systems. Either result renders these troublesome microorganisms unviable, which consequence is most desirable for best operation of water cooling systems.
The object of this invention is to provide an alginate lyase effective in water cooling systems.
Further objects and advantages of this invention will be apparent from the description thereof which follows.